1. Field of the Invention
The present invention is in the field of non-destructive testing processes employing the penetrant inspection process. The improvement resides in incorporating a fluorescent material in the remover to supplement or reinforce the fluorescent capability of the fluorescent dye contained in the penetrant which has become lodged in surface flaws.
2. Description of the Prior Art
The penetrant inspection process utilizing fluorescent dyes in the penetrant has been highly developed over many decades. In essence, the surface of the workpiece to be tested is first flooded with a penetrant composition which normally consists of a hydrocarbon oil vehicle in which there is dissolved a fluorescent dye. After a sufficient dwell time during which the penetrant finds its way into surface flaws or flaws which open to the surface, excess penetrant is removed usually by means of a remover containing an agent which is an emulsifier for the oil of the penetrant. This step is followed by the application of a developer which may be a dry developer of very finely divided particles, or it may be a suspension of particles in an aqueous or non-aqueous medium. The developer particles serve to draw out the entrapped penetrant thereby rendering visible the location and extent of any flaws in which the penetrant had become lodged. Inspection of the piece is carried out under ultraviolet irradiation making the fluorescent dye deposits visible against a relatively dark background of the workpiece surface.
A penetrant inspection process is only as effective as the ability to determine the extent and location of trapped penetrant. Fluorescent containing penetrants have become very widely used because it is easier to locate a small deposit of fluorescent dye than it is to locate a deposit of visible dye with ordinary light. Fluorescent dyes, however, are quite expensive and amount to about 25 to 50% of the total penetrant cost. It, therefore, becomes economically inadvisable to increase the concentration of dye in the penetrant which would, of course, also increase the problems of disposal of excess fluorescent dye in the penetrant.